


vernalization

by chellmibell



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Angst with a Happy Ending, Byleth has emotions and doesn't know how to process them, F/M, Feelings Realization, Hanahaki Disease, Manuela is a good doctor and a good friend - fight me, Not Beta Read, Warning: lung trauma, being told you’re a demon all your life skews your self image - who knew?, flowers in your lungs is not fun, more character tags to be added as they appear
Language: English
Status: In-Progress
Published: 2020-03-29
Updated: 2020-03-29
Packaged: 2021-03-01 01:55:06
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,808
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23377243
Author URL: https://archiveofourown.org/users/chellmibell/pseuds/chellmibell
Summary: ver·nal·i·za·tion (noun) the induction of a plants flowering process by exposure to the prolonged cold of winter.The Ashen Demon has only ever understood love, understood emotions, from watching others. She is as unfeeling as her title suggests, and has long since accepted it. The petals on her bed disagree.
Relationships: My Unit | Byleth/Claude von Riegan
Comments: 15
Kudos: 61





	vernalization

Two weeks after she starts coughing, Sothis becomes incessant in her nagging. Frankly, Byleth finds the girl’s concern over the matter excessive. The coughing had begun shortly after she and the Golden Deer had managed to find Flayn and that Monica girl hidden away deep within the catacombs. With the infirmary overtaxed by having its matron as one of its patients, she'd opted to simply ride out the illness the way she would have during her mercenary days. Had thought nothing of it even as Sothis had raged. Given both the unexpected company and the state of the ancient structures had been in, a stubborn cough was quite possibly the least concerning thing that could have happened to her that day. She’s getting rather tired of having to explain that.

_'You are tired? Ha! Try looking after a fool who does not know how to care for herself!'_

Byleth rubs her temples in a vain attempt to ward off the inevitable headache.

“The twenty years between my birth and our meeting claim otherwise.”

_'Oh? And, pray tell, precisely how did that meeting occur again?'_

Byleth does not glare at the spirit hovering at her side, but she does think about it as she reaches for the glass and water pitcher she keeps on her desk.

“It's a cough. Not a death sentence.”

_'A cough that has lasted for weeks, you cannot tell me such a thing is not even mildly concerning.'_

“I'm fine. ” Byleth hisses before downing the glass of water she pours for herself. 

_'We share a soul, to try and lie to me is quite the futile endeavor.'_

“Stop worrying.”

_'I will not!'_

As Sothis is spurred into yet another tirade over her well being, or more pointedly her perceived lack thereof, Byleth attempts to refocus on the papers and map strewn across her desk. With the Battle of the Eagle and Lion so close now, the class has gotten restless. As the days have ticked by, it's only gotten worse. Leonie and Raphael have repeatedly trained to the point of exhaustion. Others, like Marianne and Ignatz, have to be coaxed out of spiraling panic attacks. Last week she had literally carried Lysithea out of the library, Flayn having pulled Byleth out of bed in a panic, the young mage delirious with a fever by that point. Lorenz had been appalled when she'd imposed a class wide curfew the next day. Even Hilda, for all of her avoidance tendencies, has been making roundabout questions poorly disguised as gossip as during their ever increasing tea times.

Claude is the closest to grounded amongst the lot, but judging by the rising number of strange vials she's seen pop up, even he isn't immune to the building anticipation.

Considering all the strange happenings that have permeated their missions so far this year, a guaranteed non-lethal match against the other houses seems so tame to Byleth. Yet it commands the Deer's every thought. It's cute, she supposes, how enthralled they all are by the situation. It's only fair that she makes the effort to match their enthusiasm stroke for stroke, even if she doesn't really understand it.

Not that she understands emotions to begin with.

After all, what good are feelings to a demon?

The thought breaks Sothis away from her tirade. It always does.

 _'You are human,'_ she declares, old and powerful, with a weight to her voice that leaves Byleth no room to respond. _'Human, Byleth Eisner. A simple, foolish mortal. Stoic and seemingly unflappable, perhaps. And it is true you are different in comparison to any other I have come upon, but you are no demon. You. Are. Human. Do not forget that.'_

There are too many things Byleth can say to that. She could tell Sothis how she's never cried. How her father's men, seasoned warriors decades older than her, would call her a walking corpse. The clients who wouldn't go near her, frightened more by her than the ones she'd been protecting them from. Perhaps she could mention how the nuances of emotions and expressions have always confused her. How they still do. That the best Byleth can ever manage outwardly is a poor facsimile.

She could admit that she picked the Golden Deer not because she wanted to know why their leader would smile without it reaching his eyes, but whether or not he would teach her how.

She could remind Sothis that she can’t feel her own heartbeat.

Instead, she says, "You don't need to do this."

 _'I do.'_ Sothis counters with a shake of her head, _'And I shall continue to do so until you are able to comprehend it. Come now, enough of this. Back to work with you. I doubt your little fawns will appreciate you slacking off to debate this foolishness.'_

She doesn't think questioning her humanity counts as foolish, but decides against vocalizing the point. Dipping her head in acknowledgment, Byleth turns back to the stacks in front of her. A quick debate with herself has her grabbing the student roster alongside the next level of certification exams. She'd like to wait a little longer on promoting some of the class, preferring mastery over rapid advancement, but it'd be foolhardy to deny the advantages granted from the certifications.

Together they spend the next hour reviewing her student’s skills, combing over their abilities with rapt attention. Sothis offers her thoughts on each of them as Byleth reviews, even occasionally adding in something insightful rather than sarcastic. By the end of the hour they've successfully picked out which members of the Golden Deer will be taking the exams to advance before the battle. The list is much longer than she'd planned, but she can't find it in herself to worry. They've earned it.

Finished with the tests, Byleth shuffles through the second stack; a large pile of potential strategies she and Claude had concocted during one of his recent tactics sessions with her. Swiftly skimming through them, she systematically removes the more outlandish ones. Honestly, what had he been thinking when he'd suggested setting the _entire_ field on fire? Such a maneuver would create a high risk of losses on both sides. Only a truly desperate tactician would resort to such a dangerous plan. Or a violently apathetic one.

 _'That one does seem to take pleasure in pushing your boundaries,'_ Sothis interjects, peering over her shoulder at the paper, _'Perhaps it was an attempt to see just how unfeeling the “Ashen Demon” truly is.'_

It makes sense. Claude seems to delight in being transgressive, and has a natural talent at finding and pushing people’s buttons. Throwing out a theory to see how she would react isn't new for him, but it doesn't sit right.

Eventually, she counters with a small shrug. "Maybe. But Claude knows the value I put into minimizing damage to troops. Wouldn't it be a waste to test something he already has the answer to?"

 _'A reasonable assumption,'_ Sothis concedes, _'but your opinion is not the only thing that boy looks for. He watches you constantly, especially now that you are becoming more expressive. He did seem quite charmed by your smile after rescuing that Flayn girl, lest you forget.'_

Charmed. The idea that anyone, much less someone as vibrant and charismatic as Claude, could be charmed by her is laughable at best. For him to purposefully go out of his way simply for the mere chance of an expression… The thought settles itself into Byleth’s chest, an odd weight she doesn’t know what to do with.

“My face isn’t that interesting.” She mumbles through a cough, using the need to put away the now sorted plans as a means of avoiding Sothis’ bemused grin.

_‘To you, maybe. But have you not yourself said you’ve trouble understanding others? How can you be so certain of what he wants?’_

She’s coughing harder now and pours herself another glass to clear her throat. The cool liquid soothes the tickle and she clears her throat before finally countering.

“Because it’s stupid.”

 _‘No. Stupid is a grown woman who can’t even handle “a cough” without acting like a petulant child,_ ’ Sothis huffs, _‘You’ll be easy pickings on the battlefield if you insist on being stubborn like this.’_

“Neither Hannerman or Manuela will be fighting at Gronder. If anything, being sick will help even the odds between the houses.”

 _‘You truly do not comprehend the value of your own life,’_ Sothis bemoans with a sigh and a shake of her head, _‘If nothing else, promise me you will stay safe. There have been too many surprises since we came here.’_

She can't. A mercenary doesn't deal in promises, not even one turned professor. Sothis knows this.

"I will try." She offers.

_'Hmpf. Very well, I suppose that will have to do.'_

And with that, Byleth is alone.

~***~

Yellow is the first thing Byleth sees when she wakes up the morning after the Battle of The Lion and Eagle, a warm and vibrant yellow, just like the tapestry hanging in her classroom. Sore and still hazy with sleep, she forces herself up onto her elbows, trying to comprehend the sight in front of her.

A small smattering of flower petals are strewn across her pillow.

Rolling her eyes, she flops back down, burying her face into the other side of her pillow. Maybe she shouldn’t have let the Deer have all those bottles of wine during last night’s feast, even if they'd more than deserved the treat with their stellar performance. Regardless, it was far too early for her to deal with this sort of drunken nonsense, or the aftermath as it were.

Why flower petals, Byleth wants to ask them. Or better yet, why her? Pranking the other houses made much more sense in the wake of the Golden Deer’s sweeping win. A little immature perhaps, but like the wine she cannot find it in herself to deny them the indulgence. The Deer were a playful bunch and the concept of a big win deserving a big celebration was a tradition she was familiar with. Her father's men always treated themselves to an obnoxious amount of booze after completing difficult jobs. Students teasing their schoolmates at least wouldn't rack up huge bar tabs.

Sleep stubbornly not returning, she forces herself upright with a groan as her body protests the motion. Best to get this out of the way quickly, especially if whatever they'd left her needed cleaning. Byleth did not want to spend the better part of her hard earned day off dealing with some mess in her room. Rubbing the last remnants of sleep from her eyes, she takes a moment to prepare herself for whatever sight awaits her.

There is nothing.

Her room is as spotless as ever. Not a single item is out of place, from her boots to the carved figurine Manuela had given her as a house warming present, everything exactly as she'd left it the night before. Even the monastery's snowy messenger owl is still, comfortably dozing above her notice board on the perch it so loves.

Confused, her gaze wanders back down to the petals on her pillow. Picking one of the errant things up, she turns it over in her palm. It's large, about the length of her palm, a wavy oval that comes to a sharp point on one end somewhat like a dagger. A little battered and softer to the touch than the blooms in the greenhouse, but it’s clearly still fresh.

“What are you doing here?” She wonders aloud.

The slip of yellow yields no answers.

A gift? Had one of the students thought to bring her flowers and decided against just leaving them in her room? Such an action wouldn't be too surprising: both Marianne and Ignatz had been spending more time in the gardens recently. Though she'll need to chastise whoever did come in. Skillful as it was to get into her room unnoticed, entering without permission was something to be discouraged. It was already bad enough that Claude had developed a habit of wandering in as he pleased, Byleth didn't need more of them following suit.

Leaving the petal with the others, she gets up to begin her morning stretches. 

Three positions in she starts coughing; a tickle at the base of her throat that won't disperse. This stupid cold is starting to get on her nerves. She manages to get halfway through her normal routine before it becomes too much she has to stop to clear her throat. 

Except she can’t.

Coughing does nothing. Glass after glass of water fails to sooth as she continues hacking. Pressure is building in her throat, a weight she cannot shake off. Pain grows in her chest as each cough rattles through her.

She's going to hurl at this rate. 

Moments after she moves herself over the wastebasket her throat clogs up, and she’s on her knees desperately trying not to choke.

She can’t breathe. _She can’t breathe._

Eventually, mercifully, something forces its way up and out of her, the pressure and pain dying as it leaves her body. Relief floods over Byleth as she desperately gulps down air, lungs burning. Her entire body aches. 

Just a cough, she’d said. Sothis was going to have her head over this.

Desperate to wash away the bitter taste in her mouth, she decides to forgo the glass, pulling the pitcher off her desk and chugging the remaining water.

Goddess, her mouth feels like she just tried to eat a bouquet, leaves and all.

That makes her stop. She doesn’t remember eating a lot of greenery at the celebration feast, and certainly not anything that would have left her mouth feeling like she’d drunk one of Hilda’s perfumes. There should be the acidic sting of bile from vomiting but instead it's just the sensation of overwhelming vegetation. She peers back over the edge of the bin, hoping to glean a hint as to what had left such a strange aftertaste.

But what greets her is not the remnants of last night’s dinner. Instead, a flower petal sits innocently at the bottom of the bin. A single yellow petal, covered in saliva. The same kind of yellow petal as the ones on her bed.

“Shit.”

~***~

Because the stars themselves were conspiring against her, Manuela wasn't in infirmary that morning. Nor the following week. It takes a chat with her father to learn the healer is off with the knights, the Remire situation warranting a more thorough examination. He'd been taken aback by the urgency of her questions, so she'd told him about her coughing fits, careful to leave out the flowers.

Jeralt had been concerned but confident.

"Well, you have been pushing yourself pretty hard these past few months. Just take it easy if you're not feeling okay." He'd ruffled her hair, like he would when she was little, "No one's going to blame you if you need a few days to get over a cold kiddo."

She hadn't bothered to correct him.

She's not sick. She's been cursed. It’s the only explanation.

That knight. The one who'd kidnapped Flayn, who'd been with the grave robbers in the Holy Mausoleum. He must have done something to her when they'd faced off in the catacombs. It had to be either him or one of the mages under his command. No one else would have had the opportunity or skill in dark magic to do so. The coughing had started shortly after that day after all.

Surprisingly, the concerned stare Manuela fixes her with when Byleth finally catches her in the infirmary doesn’t seem to agree.

One would think the freshly coughed up petals in her hands would have made an easy argument.

“I should have known,” the older woman mutters once she’s finished checking Byleth over, fingers skimming through a medical journal, “Especially after Hannerman went on and on about your magic potential when you first arrived at the monastery. You’re so composed, I forget how young you are at times.” 

And people called her cryptic. “What does my age have to do with vomiting petals?”

“Coughing,” Manuela corrects absently, still staring down at the tome on her lap, “You’re coughing up petals. And to answer your question: everything. A person’s magic can be easily affected by their emotions, and sometimes when a person suppresses theirs enough it can cause build up. The younger the patient is, the more likely the build up will manifest as physical ailments. Fevers are the most common symptom.”

 _‘Well, that certainly explains your little Ordelia’s tendency of getting them.’_ Sothis pipes in, manifesting over the physician's shoulder to peer at the book.

Byleth nods in agreement as she gets up from the cot, moving to look over Manuela’s other shoulder. The text is dense and complicated and her eyes begin spinning the more she tries to concentrate on it. Knowing casual Almyran was handy for jobs near Fodlan's Throat but pretty worthless when faced with something clearly written in an older Adrestian dialect. Especially when in cursive.

Tapping a nail against a particular column, Manuela proceeds with her diagnosis. “What you have is Hanahaki, a rare variation of that build up. It’s also one of the most deadly. Put simply, you’re in love.”

What.

“Unrequited love to be precise.”

She was hearing things.

“You’ve buried the emotion so thoroughly your body couldn’t take the pressure and your magic energy responded by creating the flowers in your lungs as an outlet. A way of forcing you to express your feelings, as it were.”

“That doesn’t make sense.” Whatever curse the Death Knight had placed on her finally got to her brain and she was hallucinating.

Manuela smiles at that. “I know. Flowers growing in your lungs sounds like something from a fairy tale, doesn’t it?”

“No, not that. The flowers I understand. I help out in the greenhouse all the time,” there’s also a pointy-eared child living in her mind who granted her the ability to rewind time itself, flowers born from magic are nothing, “I’m saying the diagnosis is wrong. I’m not in love.”

Manuela doesn’t even bother to grace her with a verbal response, simply waving one of the petals she’d brought in Byleth’s face instead.

“I’m not in love,” She repeats, shoving the hand away, “I don’t… I don’t feel emotions. I never have. Not like a normal person anyway.”

If the silence that followed the admission wasn’t bad enough, paired with the look Manuela gives her is enough to make Byleth question if she should rewind the conversation. She might well have done so if Sothis hadn’t swiped at her for the thought. 

A hand grabs her own, pulling Byleth out of her thoughts.

“Professor,” Manuela begins, gently squeezing her hand, “Byleth. There is no one alive who doesn’t feel something. Just because you don’t experience things as intimately as someone else doesn’t mean your emotions don’t exist. Please don’t belittle your own feelings because you don’t think they’re enough. They _are_.”

Her free hand hovers over her chest, where her heart sits silent. No one alive. Did that mean she was dead then? 

“But to love something enough to make me sick…”

“Shows just how much you care despite what you’ve let yourself believe,” Manuela interjects, punctuating the statement with a pat on the spot next to her, “Now sit down so we can start treating you properly. Honestly, you’re worse than some of the students here.”

Sothis laughs, snickering even harder at the glare it earns her. _‘Well, she’s not wrong!’_

Ignoring the girl, Byleth does as she’s told, letting the older woman’s magic drape over her. Warmth sinks bone deep into her, easing the ache left behind by her coughing. Air comes easier too, and it is only then does she realize how shallow her breathing has been the past few weeks.

Manuela gives her a quick once over when she finishes, before moving to make notes on her chart. “Now, I’ve treated the secondary symptoms, but that’s really all I can do for you. Hanahaki is caused by a person’s emotions, and ultimately can only be cured by them.”

“You can’t be serious.”

Manuela shrugs, “I’m afraid so. It’s entirely possible you’ll fall out of love, which will naturally clear up everything in the process providing the symptoms haven’t become too severe by that point. Even then, once the source is gone it’s a matter of regular healing sessions to undo any remaining damage.”

What kind of cure was that? How was she supposed to fall out of love if she had to be told she was even _in_ love?

“Similarly, you’ll get better if the person you’re in love with returns your affections. Openly and truly loves you back, not some wishy-washy ‘I think I like you too’ nonsense like that dip of a knight from my last date.”

That was even less likely. The fondness the students had for her was the most affection anyone outside of Jeralt had ever shown her. 

No one sane would ever actually love her.

“Your recovery depends on you, Professor.” 

Wait.

“That’s it? There’s nothing else? ” 

The wince Manuela gives her says volumes. “Nothing that wouldn’t put you at too great a risk to use as anything other than a last resort.”

Last resorts she could work with. She’s managed to pull wins from low odds before. 

“What kind of risk?”

“The kind that could end with you dead on my operating table.” Byleth had seen Manuela bring too many knights back from the brink since she’d arrived to not understand the weight of those words. “There are records of cases where patients whose disease progressed too far underwent surgery to remove their flowers. It’s a very long and complicated process, with an extremely low survival rate. I pride myself on my work as a physician Professor, but I wouldn’t even consider attempting such a procedure on you unless you were already dying.”

Meaning she really had no other options.

Dammit.

 _‘Enough. Do not dismiss what you have learned here.’_ Sothis whispers to her, fingers ghosting through Byleth’s hair, _‘You know what you’re facing now. That alone is worth the effort.’_

Something must be showing of her face for a change because almost immediately after Sothis stops talking, Manuela offers her a compromise: healing lessons.

“I can’t cure you Professor, as much as it galls me to admit it, but I refuse to let you suffer because of that. Simple and mind-range healing spells will help alleviate the worst of your symptoms.” She slides a small textbook into her hands. “You can pop by whenever you have the time. For a lesson or even just to talk. My door is always open for you.”

Byleth nods. It wasn’t much but it would have to do.

**Author's Note:**

> I started theorizing a hanahaki!Byleth oneshot around October last year. Several months, 5000+ words, and the realization I wasn't even halfway done later, my usual write a oneshot and disappear process wasn't viable anymore. This is my first time writing for the series, and first time doing a multi-chapter story in a decade so some patience would be appreciated ❤


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